[API reference](https://evolu.dev/docs/api-reference) › [@evolu/common](https://evolu.dev/docs/api-reference/common) › Assert

Runtime assertions for invariants and value checks.

## Functions

| Function                                                                               | Description                                                                                                                                                                                                  |
| -------------------------------------------------------------------------------------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------ |
| [assertEqual](https://evolu.dev/docs/api-reference/common/Assert/functions/assertEqual)             | Asserts that two [Data](https://evolu.dev/docs/api-reference/common/Type/variables/Data) values are equal according to [eqData](https://evolu.dev/docs/api-reference/common/Eq/functions/eqData).                                      |
| [assertErr](https://evolu.dev/docs/api-reference/common/Assert/functions/assertErr)                 | Asserts that a [Result](https://evolu.dev/docs/api-reference/common/Result/type-aliases/Result) is an [Err](https://evolu.dev/docs/api-reference/common/Result/interfaces/Err), optionally compares its error, and narrows the Result. |
| [assertNotDisposed](https://evolu.dev/docs/api-reference/common/Assert/functions/assertNotDisposed) | Guards synchronous methods on objects that may be called after disposal.                                                                                                                                     |
| [assertOk](https://evolu.dev/docs/api-reference/common/Assert/functions/assertOk)                   | Asserts that a [Result](https://evolu.dev/docs/api-reference/common/Result/type-aliases/Result) is an [Ok](https://evolu.dev/docs/api-reference/common/Result/interfaces/Ok), optionally compares its value, and narrows the Result.   |

## Variables

| Variable                                                                                                   | Description                                                                                                         |
| ---------------------------------------------------------------------------------------------------------- | ------------------------------------------------------------------------------------------------------------------- |
| [assert](https://evolu.dev/docs/api-reference/common/Assert/variables/assert)                                           | Ensures a condition is true, throwing an error with the provided message if not.                                    |
| [assertFalse](https://evolu.dev/docs/api-reference/common/Assert/variables/assertFalse)                                 | Asserts that a value is exactly `false` and narrows it to `false`.                                                  |
| [assertNonEmptyArray](https://evolu.dev/docs/api-reference/common/Assert/variables/assertNonEmptyArray)                 | Asserts that an array is non-empty.                                                                                 |
| [assertNonEmptyReadonlyArray](https://evolu.dev/docs/api-reference/common/Assert/variables/assertNonEmptyReadonlyArray) | Asserts that a readonly array is non-empty.                                                                         |
| [assertNonNullable](https://evolu.dev/docs/api-reference/common/Assert/variables/assertNonNullable)                     | Asserts that a value is non-nullable.                                                                               |
| [assertNotNull](https://evolu.dev/docs/api-reference/common/Assert/variables/assertNotNull)                             | Asserts that a value is not null while preserving undefined.                                                        |
| [assertNotUndefined](https://evolu.dev/docs/api-reference/common/Assert/variables/assertNotUndefined)                   | Asserts that a value is not undefined while preserving null.                                                        |
| [assertSame](https://evolu.dev/docs/api-reference/common/Assert/variables/assertSame)                                   | Asserts that two values are the same according to [eqStrict](https://evolu.dev/docs/api-reference/common/Eq/functions/eqStrict). |
| [assertTrue](https://evolu.dev/docs/api-reference/common/Assert/variables/assertTrue)                                   | Asserts that a value is exactly `true` and narrows it to `true`.                                                    |